Apparatus for recording steep wave front voltages of short duration



N 1931. L. K. 5mm ET AL 2,0915% APPARATUS FOR RECORDING STEEP WAVE FRONT VOLTAGES OF SHORT DURATION Filed NOV. 5, 1935 INVENTORS JZTSwarZ pii BY J WBodle (9 ATTORNEY Patented Nov. 2, 1937 UNITED STATES APPARATUS FOR RECORDING STEEP WAVE FRONT VOLTAGES SHORT DURATION Leland Kasson Swart, Mountain Lakes, and David William Bodle, Peqnannock, N. J., assig'nors to American Telephone and Telegraph Company, a corporation of New York Application November 5, 1935, Serial No. 48,378 7 Claims. (01. 175-320) This inventionrelates to gas-filled tubes and circuits therefor. More particularly, this invention relates to recording systems employing gasfilled tubes and circuits. Still, more particularly, this invention relates to arrangements for recording short-lived surges, particularly if of steep wave front.

Where a telephone or other line is exposed to extraneous voltage efiects of steep wave front, such effects, if produced by lightning discharges; will be of but short duration. Ordinary recording apparatus for obtaining some picture of the lightning or other such phenomena will ordinarily have a. time constant too large to be properly responsive to effects of such brief duration. The arrangements to be described hereinafter and the features and principles employed therein will be useful for the purpose of accurately translating and recording such phenomena.

Where hot cathode tubes as, for example, those of the ionic type, are employed to record steep wave front surges that persist for very short periods of time, an incomplete record will result if the recording mechanism associated withthe anode of the tube has an appreciable amount of inductance which is not shunted by resistance .or capacity. This is due to the fact that an impulse applied to the grid and cathode at the input of the tube which results in ionization of the gas within the tube may be of too short duration to produce ionization in the anode-cathode circuit. This follows from the lack of sufficienttime during the interval that the surge persists on-the input terminals to build up suflicient current through the recording mechanism connected in series with the anode and cathode of the gas-filled tube. This difficulty can be overcome by the use of a suitable resistance or a condenser in shunt with the inductive load mechanism. This resistance or condenser must be of such a value as to allow sufilcient current to be by-passed around the load mechanism to produce ionization by. collision in the work circuit even for very short-lived, steep wave front impulses.

The use of gas tubes'requires that a critical minimum value of current be passed between the anode and cathode to produce a locked-in con dition of the tube. The resistance or condenser must therefore be of suitable value to instantly allow that value of current, or a greater current, to be passed through the work circuit independently of the current supplied to the anode of the tube through the load mechanism.

place until the recording mechanism or message register, of the type well known in the telephone 7 art and employed for recording the number of telephone calls made on a particular telephone line, has had ample time to operate. Hence, to

avoid design difficulties it is generally simpler.

to employ a resistance to shunt the operating mechanism.

This invention will be better understood from the detailed description hereinafter following when read in connection with the accompanying drawing which illustrates certain arrangements for carrying out the principles of this invention.

Referring to the drawing, the reference character G designates a heater type of gas-filled tube, the input or grid-cathode circuit of which is connected to a source of voltage to be recorded through a resistor R1 and a source of biasing voltage B1. The output or anode-cathode circuit includes a source of anode voltage B2 and the winding of an operating relay M1 The armature and contact of relay M1 controls the operation of a second relay M2 which may be a message register or other recording instrument. The winding of the latter relay is in series with a source of potential B3 which supplies the current required for its operation. The armature and contact of relay M2 are in series with a condenser Cl which shunts the winding of relay Mr.

A large resistor R2 permanently shunts the latter winding, but if desired, a condenser C2 (shown in dotted lines) instead may permanently shunt the winding of relay M1. A spark killing circuit comprising a resistor R3 and a condenser C: will shunt the armature and contact of relay M1 and, if desired, a similar arrangement of resistor R4 and condenser C4, shown in dotted lines, may be employed to bridge the armature and contact of relay M2, the latter circuit being employed for a different purpose, as will appear hereinafter.

If the voltage applied in series with resistor R1 and battery B1 is of sufllcient magnitude and duration, ionization will be producedin the gridcathode circuit. This ionization will allow an appreciable current to be built up in the anodecathode circuit. The relay M1 will then operate and its contacts will cause the message register or recording device M2 to be operated. Upon operation of device M2, the condenser C1 will be connected to shunt the winding of relay Ml and allow the tube G to reset to normal just as soon as the potential applied to the grid-cathode circuit is withdrawn. Both relays M1 and M2, however, will remain operated during the period of application of voltage to the grid-cathode circuit of tube G. a

If the condenser C1 (unless of certain wellchosen value) were connected across the winding of relay M1 at all times, it would be possible for the operating relay M1 and tube G to be reset to normal before the recording mechanism, namely relay M2, could properly operate. Thus, the apparatus would fail to record very shortlived, steep wave front impulses. Accordingly, the condenser C1 becomes shunted across the winding of relay M1 only after operation of relay M2. The resistor R2 or the condenser C2 is employed to provide for the almost instantaneous passage of current from battery B2 through the path formed by the anode and cathodeof tube 'G. If both resistor R2 and condenser C2 were omitted, however, the current supplied by battery B2 would have to traverse the winding of relay M1 and this current would not build up fast enough to a required value to produce ionization by collision of the, gas' between the anode and cathode of the tube. The delay would be caused by the inductance of the relay winding and hence relay M1 would fail to operate on the application of very short surges to the input circuit of the tube. The addition of either resistor R2 or condenser C2 in shunt with the relay winding permits the current of battery B2 to rise instantaneously and the ionization of the gas within the tube becomes sufficient so that battery B2 may transmit current to lock the tube in. Ample time is allowed thereafter to operate relay M1 by current derived from battery B2. The addition of condenser C2 is preferred as against the resistor R2 because the condenser, cooperating with the winding of relay M1, provides for the resetting of the tube G. This latter resetting feature is described in the D. T. Osgood application, Serial No. 27,793, filed June 21, 1935.

If no indicating device or message register such as M2 is connected to the system and it is desired to reset the apparatus immediately after withdrawal of the applied voltage at the input circuit, the condenser (31 may be shunted around the winding of relay M1 without the shunting resistor R2. If desired, a resistance (not shown) may be inserted in series with condenser C1 in shunt with the winding of relay M1.

Fast operation and automatic resetting after message register operation can be accomplished by omitting resistor R2 and adding the resistor R4 and condenser C4, as shown in dotted lines. The resistor R4, however, must be high in value in order that automatic resetting of the tube G may take place only after message register operation.

For good recorder practice, the resistor R4 and condenser C4 may be entirely dispensed with and the arrangement shown in full lines, including resistor R2 and condenser C1, employed.

The use of resistor R2 is not necessarily confined to resetting arrangements as shown, but

may be employed to shunt any operating or load device connected, for example, between the anode This type of tube is by no means odes being connected to the upper terminal of resistor R2 and the left-hand terminal of source B2, respectively. The two cathodes will form one discharge gap and the anode and associated cathode will form another discharge gap.

While this invention has been described as embodied in particular arrangements which are deemed desirable, it is to be understood that it is capable of. embodiment in many and widely varied forms without departingv from the spirit and scope of the invention as defined in the appended claims. 7

What is claimed is: 1. Apparatus for translating steep wave front voltages of short duration including a gas-filled tube to the input circuit of which said voltages are applied to ionize the ,gas within the tube, a source of potential, an inductive load connected to the output circuit of the tube in series with said source of potential, and a resistor conductively connected directly in shunt to the inductive load.

2. The combination of a gas-filled tube having input and output circuits, an inductive load operatively associated with the output circuit of said tube, a non-inductive impedance connected in slnmt with said load, a capacitor, and means controlled by the load for shunting the capacitor across the load.

3. The combination of a source of voltage, an inductive load, a gas-filled tube interconnecting the source and the load, a non-inductive impedance connected in shunt with the load, a condenser,-and means responsive to the transmission of voltage from said source through said tube to the load to shunt the condenser across the load.

4. The combination of a gas-filled tube having an input circuit and an output circuit, an inductive load connected. in the output circuit and controlled by voltages applied to the input circuit, the gas within the tube being ionized by the voltages applied to the input circuit of the tube, and a resistor conductively connected directly in shunt with the load.

5. Apparatus for recording steep wave front voltages of short duration comprising a gasfilled tube having an input circuit to which the voltages are applied and an output circuit, a relay having a winding connected in the tubes output circuit, a resistor in shunt with the relay winding, a recording device controlled by the first-mentioned relay, a condenser, and means responsive to the operation of said recording device to shunt the condenser across the winding of the first-mentioned relay.

6. The combination of a gas-filled tube having input and output circuits, an inductive device connected to the output circuit of said tube, a resistor connected in shunt with the inductive device, a capacitor, and means responsive to the ionization of the gas within'the tube for shunting the capacitor across the inductive device.

7. The combination of a gas-filled tube having LELAND KASSON SQWART. DAVID WILLIAM BODLE. 

